Jets did that last season with Enron Riley and Austin Howard...They were part of the 53 man roster for over half the year IIRC and I don't believe they were ever active (maybe Riley was for Den)

Austin Howard obviously had more than just intel gathering purposes, being he is out starter.

sec.101row23,

You are right in suggesting that we need another back, being that we are only carrying two right now with the injuries (3 if you include hilliard).

I do not believe that a RB with bell's characteristics are what we need, however.

check this excerpt out:

unning back Khalil Bell was UCLA's only participant at the NFL combine, and his numbers were mixed. He ran an unimpressive 4.68 seconds in the 40-yard dash and his 15 reps in the 225-pound bench press didn't left him nine shy of being in the top 10 of running backs.
However, he was third in the 60-yard shuttle (11.55 seconds), and tied for fifth in the three-cone drill (6.87) and 20-yard shuttle (4.20).